Dye images can be formed by the reaction of dye forming couplers (hereinafter referred to simply as couplers) with the oxidation product of aromatic primary amine developing agents when silver halide color photographic materials are exposed to light and then subjected to color development.
In such a system as described above, color reproduction is generally achieved by subtractive color photography. Yellow, magenta and cyan dye images having the relationship of complementary colors to light are formed to reproduce blue, green and red colors. Generally, acylacetamide couplers and malondianilide couplers are used as yellow dye forming couplers (hereinafter referred to as yellow couplers) to form a yellow dye image; 5-pyrazolone couplers and pyrazolotriazole couplers are used as magenta couplers to form a magenta dye image; and phenol couplers and naphthol couplers are used as cyan couplers to form a cyan dye image.
The yellow dye, magenta dye and cyan dye obtained from these couplers are generally formed in silver halide emulsion layers sensitive to radiation having a relationship of complementary colors to the radiation absorbed by the dyes or in layers adjacent thereto. The application of color couplers to sensitive layers is not limited to the above-described layers, and color couplers can be employed in light-sensitive layers which do not have such a relationship of complementary colors to light as described above. For example, color couplers can be used in silver halide emulsions sensitive to the infrared ray region.
Of the above-described couplers, phenol couplers and naphthol couplers are conventionally used as cyan dye forming couplers. This is because these couplers have fully satisfactory performance with regard to the reactivity thereof with the oxidation product of developing agents. However, the absorption of dyes obtained from these couplers are broad and extend into the green light region. In addition, the dyes have secondary absorption in the blue light region. The above-described absorption characteristics are disadvantageous properties in color reproduction and have a serious effect on the reproduction of blue color and green color.
Various attempts have been made to improve the absorption characteristics as described above. For example, European Patent Application 0 249 453 A discloses diphenylimidazole type cyan couplers wherein absorption in the short wavelength side is sharp. U.S. Pat. Nos. 4,873,183 and 4,916,051 disclose cyan couplers having a pyrazoloazole skeleton. JP-A-63-281161 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and JP-A-63-280247 disclose cyan couplers having a pyrazolobenzimidazole skeleton. However, all of these couplers have poor developability, that is, they have poor reactivity with the oxidation product of p-phenylenediamine developing agents, and dyes formed have low fastness. Accordingly, a further improvement is required.
European Patent Application 0 456 226 A1 discloses pyrrolopyrazole cyan couplers which have relatively high developability and have excellent developed dye hue. Further, the fastness of the dyes formed therefrom to heat is greatly improved in comparison with the above described couplers.
However, it was found that the fastness of dye images formed from these couplers is poor under high temperature and humidity conditions particularly in the low density region. Further, it was found that when these couplers are present in light-sensitive materials and developed, color mixing is increased, even though absorption spectra have excellent characteristics.
As described above, phenol couplers and naphthol couplers conventionally used have a disadvantage in their spectral absorption characteristics. A problem to be solved from the standpoint of improving the spectral absorption characteristics is the color mixing caused by the movement of the oxidation product of the developing agents during processing, and another problem to be solved is poor fastness of dye images during storage under high temperature and humidity conditions. The former problem can be reduced by increasing the coating weights of color mixing inhibitors. However, when the coating weights of the color mixing inhibitors are increased, the thicknesses of layers are increased, and problems occur in that sharpness is lowered, and the load in conducting rapid processing is increased.
The present inventors have conducted research to solve the problems associated with prior art, and the present invention has been accomplished as a result of this research.